Comparison of external apical root resorption in maxillary anterior teeth following en-masse versus two-step retraction: a 3D volumetric CBCT-based randomized controlled trial.

Authors

Hiba Tabassum, Imtiaz Ahmed, Saba Arshad, Erum Bahroz Khan, Sadia Rizwan, Sarfaraz Hussain

Published in

Clinical oral investigations. Volume 30. Issue 9. Aug 29, 2026. Epub Aug 29, 2026.

Abstract

Comparison of external apical root resorption (EARR) between space-closure techniques remains inconsistent due to 2D imaging limitations. This study aimed to quantify and compare EARR in maxillary anterior teeth following en-masse versus two-step retraction using 3D cone-beam computed tomography (CBCT).
This prospective randomized controlled trial included 60 male and female patients (mean age 19.87 ± 4.01 years) requiring bilateral maxillary first premolar extractions and maximum anchorage. Participants were randomly allocated to en-masse retraction (210 g/side) or two-step retraction (70 g canine retraction, then 140 g incisor retraction). CBCT scans were obtained before (T1) and after (T2) space closure. Three-dimensional root models were reconstructed using Mimics software. Linear root length and volumetric changes were compared (Mann-Whitney U test; p < 0.05).
Both groups exhibited statistically significant reductions (p < 0.001) in root length (two-step: -0.56 ± 0.09 mm; en-masse: -0.57 ± 0.11 mm) and root volume (two-step: -8.88 ± 3.24 mm³; en-masse: -10.12 ± 4.49 mm³). No statistically significant differences were observed between techniques for any tooth or overall mean values (p > 0.05). Lateral incisors showed the greatest linear resorption in the two-step group, while volumetric reductions were substantial across central incisors and canines.
En-masse and two-step space closure produce comparable linear and volumetric resorption; neither technique confers a protective or detrimental advantage regarding EARR.
Neither retraction technique increases the risk of EARR, allowing clinicians to select either approach without concern for differential root resorption when biomechanical control is appropriately maintained.
The trial was registered at ClinicalTrials.gov: NCT05606185 on October 31, 2022 (first posted: November 4, 2022; ( https://clinicaltrials.gov/study/NCT05606185 ).

PMID:
42667330
Bibliographic data and abstract were imported from PubMed on 30 Aug 2026.

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